a) Field of the Invention
The invention is directed to a vacuum valve with a conical sealing surface which is arranged at a valve body and which surrounds a valve opening, a valve disk which is rotationally symmetrical with respect to its center axis and at which a conical sealing surface is arranged and which is displaceable between an open position in the open state of the vacuum valve and a closed position in the sealed state of the vacuum valve, the movement of the valve disk when closing the vacuum valve taking place, at least in a final part of the closing movement before reaching the closed position, in a closing direction extending parallel to the center axis of the valve disk, and with a sealing ring having a first sealing surface and a second sealing surface which are pressed against the sealing surface of the valve body on one side and against the sealing surface of the valve disk on the other side in the closed position of the valve disk. The valve disk, the valve body and the sealing ring are made of metal at least in the areas of the sealing surfaces.
b) Description of the Related Art
A vacuum valve of the type mentioned above which is constructed as an all-metal valve is known from U.S. Pat. No. 4,458,905. This is a proven construction that is used particularly for high-vacuum applications. However, a disadvantage of this vacuum valve consists in that the force to be applied for tightly closing the valve (closing force) is relative large.
Another vacuum valve of this type is known from DE 44 46 947 C2. In order to reduce the required closing force, the sealing ring in this vacuum valve has a necked-down portion which is located in the area between the two sealing surfaces and which is formed by a V-shaped construction (with an opening angle greater than 90°) of the two side surfaces which connect the sealing surfaces. While this reduces the required closing force, this closing force is still relatively large.
DE 26 23 906 A1 discloses a vacuum valve in which the valve disk is provided with an annular disk that projects outward. The outward circumferential narrow side of the disk is rounded and forms a sealing surface. The disk is constructed so as to be flexible in the manner of a disk spring and extends forward diagonally (with reference to the closing direction), i.e., viewed in longitudinal section, it encloses an angle of less than 90° with the closing direction of the valve disk. The outer sealing surface of this disk cooperates with a conical sealing surface at the valve body. A disadvantage of this valve consists in that a deficient tightness of the valve can result even with very close tolerances of the geometry of the disk and sealing surface of the valve body, for example, roundness defects. Also, snap effects can occur when the valve is opened, particularly when the valve has been heated. For this reason, this vacuum valve has not had practical success.
Further, AT 396 285 B discloses a vacuum valve in which an actuation member which is constructed in the manner of an expanding cone cooperates with a saucer-type closure member. For this purpose, a ring disk is constructed integral with the saucer-type closure member. When the actuation member moves in, the ring disk which is constructed in the manner of a disk spring forms a spreading element which presses the saucer-type closure member outward so that an outer sealing edge of the saucer-type closure member is pressed against a conical sealing surface of the valve body in order to seal the vacuum valve. This vacuum valve requires a relatively large force for closing tightly. Further, relatively slight geometric inaccuracies in this vacuum valve lead to deficient tightness of the valve.